Heavy work vehicles known in the building sector are known, normally consisting of a truck on which an articulated arm is mounted to distribute and cast concrete.
Known articulated arms consist of a plurality of segments, pivoted to each other and folding back on each other, so as to assume a folded configuration with minimum bulk, positioned close to the truck for transport and movement on the road, and working configurations that allow to reach areas that are even very far from the truck.
Articulated arms also comprise a plurality of actuators, generally linear actuators, each associated with a pair of segments and configured to allow the reciprocal rotation of the segments.
One of the end segments, in particular the innermost segment, is associated with a support and rotatable movement tower mounted on the vehicle and configured to support the articulated arm and to allow it to rotate around a generally vertical axis of rotation.
The support and rotatable movement tower can be equipped with an actuator, generally a rotary actuator, suitable to allow the articulated arm to rotate around said axis of rotation.
Another linear actuator can be provided between the support and rotatable movement tower and the end segment of the articulated arm to allow the latter to rotate around a generally horizontal axis of rotation.
Both the linear actuators and the rotary actuator are generally the hydraulic type and are connected to a command circuit, typically controlled by a control and command unit.
In fact it is known that, if the linear actuators and the rotary actuator are the hydraulic type, the control and command unit is configured to control and command the delivery rate of fluid in the command circuit and, selectively, in at least one of the linear actuators or the rotary actuator.
The entity of the delivery of fluid, commanded in the linear actuators and the rotary actuator, allows to manage the speed of reciprocal rotation of the articulated segments in order to take, with a predetermined value of speed, the external terminal end of the articulated arm with which the concrete delivery element is associated, to the predefined position.
It is also known that, for reasons of safety, the speed of rotation of the articulated segments is limited by specific regulations so that the terminal end of the articulated arm moves with a predefined peripheral speed, lower than a maximum limit.
A regulation is known, for example, which sets an upper limit for the speed of movement of the terminal end to 0.75 m/s, if a linear actuator is used, to 3.00 m/s if several linear actuators are driven simultaneously, and to 1.5 m/s if the rotary actuator of the support and rotatable movement tower is used.
It is also known that the speed of movement of the terminal end is a function not only of the actuation speed of every individual actuator, and hence the angular rotation speed of the one or more segments that are made to rotate by the actuator/actuators, but also of the geometric configuration of the articulated arm and, in particular, the position assumed by the terminal end of the articulated arm.
Indeed it is known that the speed of movement of the terminal end of the articulated arm is given by the product of the angular rotation speed of the segment and the distance of the terminal end from the point of rotation.
It is also known that, in the case of actuators of the hydraulic type, their actuation speed is determined by the delivery rate of work fluid that is pumped into them.
It is also known that current forms of embodiment calculate the limit value of the speed of movement of each segment considering a completely extended configuration thereof. In this case, therefore, the distance of the terminal end from the point of rotation is fixed and equal to the overall length of the articulated arm in its extended condition; consequently, to respect the limit speed condition of the terminal end, the maximum angular rotation speed of each segment must be less than a predefined fixed value.
This condition is the most precautionary one for the movement of the articulated arm and ensures that the speed of the end of the articulated arm never exceeds the set limit, whatever its position.
However, in most cases, the arm is not in the extended configuration and the conditions imposed above entail a slow-down of the movements of the articulated arm above the constraints established by the regulations.
This has a negative effect on the times required for repositioning the articulated arm and hence on the productivity of the machine on which it is mounted.
A device to move an articulated arm is known from the European patent application EP 1939134 A2 (EP'134), which comprises sensors able to detect the positions of the segments that make up the articulated arm and to command its components, by means of an intelligent control device, according to a planned movement.
However, this planned movement is determined to allow to move the terminal end of the arm to a desired position, at the same time keeping the terminal end on a straight line or in a plane.
There is no reference to any control of the position of the terminal end of the arm with reference to a maximum speed of movement determined by regulations.
Consequently, the device known from EP'134 does not provide any planning or regulation of the speed of movement of the components of the articulated arm in order to optimize the movement and repositioning speed while still respecting the regulations: it therefore suffers from the same disadvantages as the known solutions as described above.
One purpose of the present invention is to perfect a method and obtain an apparatus for moving an articulated arm which makes the movement operations very quick yet still respects the safety norms imposed, thus guaranteeing an increase in productivity thanks to the reduction in the times required for repositioning the arm.
Another purpose of the present invention is to perfect a method and obtain an apparatus for moving an articulated arm that is simple and efficient.
Another purpose of the present invention is to perfect a method for moving an articulated arm that allows to increase the speed of movement of the articulated arm compared with known solutions
The Applicant has devised, tested and embodied the present invention to overcome the shortcomings of the state of the art and to obtain these and other purposes and advantages.